WF-139 one-sided charging bay failure

[Brizzler]

So I just acquired a WF-139 charger in a trade on CPF B/S/T. The guy I traded with told me he bought the charger on lighthound a few months ago, had only used it a few times, had never had problems with it and had never tried to open it.

Unfortunately, yesterday when I tried to use it I discovered that only the left charging bay works as it should. :shakehead In the right bay the LED changes to red when a cell is inserted, but it doen't the do anything much. While the left charging bay gives a 4.88V no-load voltage across the terminals, I get a fluctuating 0.00V-0.01V on the right.
I opened the charger yesterday and found nothing obviously wrong based a quick visual comparison with photos on the forums, though one of the tabs holding the two halves of the charger case together was broken.
I can't see how this problem could possibly have come about during shipping.

For the moment it is presumably safe to at least continue using the side that works. Any suggestions on how to repair the charger? Or should I just put this down to experience as a trade gone a bit bad, bin the charger and buy a new one? :duh2:

I would be grateful for some advice!
Thanks! :wave:

 

[buickid]

Could be a trade gone bad, or shipping could have killed it. Contact the seller perhaps. In any case, I'm not sure its worth repairing...

 

[VidPro]

isnt it a simple parellel charger? you got it apart already, can you do a conductivity test from the board to the metal battery connecting tabs.
that would be simple, and easy to resolder them, and other than any actual component problem, that connection gets moved/flexed , each time you put a battery in, so it might be more likly to fail.
(put DMM meter in resistance check mode, and test between the solder blob and the metal tab, making sure you make connection , because there can be flux and board coatings)

if its protected from being parellel (one hot battery hitting a discharged one) then mabey a simple diode in there broke open.
that also goes along with your 4.8v Open no-load voltage, that there is a .6-.7volt dropping type of diode leading from the dc power source to the battery connector, probably at the + side, but it could be either side.
then you got a big 0 on the other side, so find the diode, and do a diode test across it, with nothing connected , and no battery in.
or
with power connected and being very carefull, track back the 4.8v from the working side, one or 2 compenents back, then fwd trace that voltage to the other side, somewhere in the foreward tracing you will go from something to nothing, then locate the part , and if you replace the diode it would need to be of the same type, or you will make an exploding charger

 

[Brizzler]

buickid: I've already contacted the seller, who told me he'd never had a problem and never tried to open it. :thinking: Must admit I find this hard to believe...:shakehead

VidPro: thanks for the advice, I'll see what I can do, though I won't do any testing with the power connected and the case open, don't want to go

 

[mdocod]

Hello VidPro,

The WF-139 is not a parallel charger, you may be mistaking it with the DSD, which is a single channel charger with 2 slots wired parallel. The WF-139 has independent circuits on each side.

-Eric

 

[buickid]

If its of any use to you, the WF-139 has two screws, one is at the top, the other is underneath the sticker, which must be peeled back or pierced. I tried removing the sticker and its rather obvious that it was removed. - Trevor

 

[stefanj]

There is a lot of this type of problem on the Forums on DX for this charger. Not saying the seller tried to rip you off or anything- but this does seem to happen on a regular basis. I would look at getting a new charger (the Trustfire (sku009) has the same board and components of the WF-139 and is pretty cheap on DX- of course you run the risk of the same thing happening. I just got the DSD charger and have no compliants on it or the single cell Nano chargers. Or just use the one channel and plan your battery usage carefully. Sorry you had a deal go bad- but hey I do have a Trustfire charger with one fried channel(I fried it- my own fault) if you want it it's yours- just pay shipping.

 

[Brizzler]

Sorry you had a deal go bad- but hey I do have a Trustfire charger with one fried channel(I fried it- my own fault) if you want it it's yours- just pay shipping.

Thanks for the kind words and the offer, but I'll pass, thank you.
I think if I can't spot the problem with a bit of conductivity testing I'll probably live with it as it is -at least until I get too frustrated with it and buy another (brand new) charger. Thanks also for pointing out the DX charger options I wasn't aware of!